QUALITY CONTROL

1. QUALITY CONTROL UNIT I

2. Meaning of quality • Excellence of a product or service • Fitness for use - Juran (1974) • conformance to requirements or specifications – Crosby (1979) • Grade • Degree of preference • “The quality of a product or service is the fitness of that product or service for meeting or exceeding its intended use as required by the customer”.

3. Quality Characteristic A physical or chemical property/element(s) that are used to define the nature of the product or service (which contributes to fitness for use) is a quality characteristic. Can be classified as: Technological/Structural – length, Weight, Strength, dia., frequency, etc. Psychological (Sensory) – taste, odour, beauty etc. Time-oriented – Reliability, maintainability, Warranty etc. Ethical – Honesty, Integrity etc.

4. Quality characteristic Quality characteristic may be 1. Directly measurable - weight, shear strength, Sp. Gravity, length, dia. Etc. 2. Non-measurable - rejections due to flaws, cracks, breakages etc.

5. Quality characteristic Fall in to two broad classes – Variables - Measurable, Expressed on a numerical scale and Attributes - if classified as either conforming or nonconforming to a stipulated specification

6. Nonconformity and Nonconforming Unit • A nonconformity is a quality characteristic that does not meet its stipulated specification. • Example • A nonconforming unit has one or more nonconformities such that the unit is unable to meet the intended standards and is unable to function as required. • Example

7. Defect and Defective • Nonconformity - Defect and • Nonconforming Unit - Defective

8. Quality of Product/Service Quality of Design Quality of Conformance Quality of performance

9. Quality of Design “ The product or service must be designed to meet at least minimally the needs of the consumer”. Design should be simplest and least expensive while still meeting the customer’s expectations. Yield strength (customer requirement) = 100kg/cm2 “Tightness of the specifications for manufacture of the product” Tolerance : ± 0.001 mm and ± 0.01mm

10. Quality of Design Factors controlling Quality of Design • Type of customers in the market • Profit policy of the firm • Environmental conditions • Special requirements of the product

11. Cost or Value Vs. Designed quality level (Quality of Design)

12. Quality of Conformance “ The manufactured product or the service rendered must meet the standards selected in the design phase”. Defect prevention, finding, analysis and rectification Factors controlling Quality of conformance • Adequate quality of incoming raw material • Adequate machines tools and measuring instruments • Proper selection of process • Trained operators • Proper storage and shipment • Feedback from internal inspection and customers • Use of S.Q.C. techniques

13. Quality of performance “ How well the manufactured product functions or service performs when put to use”. Measures the degree to which the product or service satisfies the customer. Function of Quality of design Quality of conformance

14. Quality of service Service Industries • Retailing • Distribution • Financial services – banking, insurance • Hotels and tourism • Leisure, recreation, entertainment • Professional and business services like accountancy, marketing, law, consulting • Healthcare • Software etc.

15. Continue… • Service is intangible - it cannot be easily measured, tested and verified in advance of sales to assure quality • Services are perishable • Precise standards like manufacturing can rarely be set • It is created and consumed simultaneously or near simultaneously • Service Production and Consumption are often inseparable i.e. Customer is in service factory.

16. Continue… • Services offered can vary from “Producer to Producer” e.g. outlet to outlet • Outcome of Service is as important as process of delivery. assessment of quality is made during the service delivery process. • Service Quality is more difficult for customer, to evaluate, than product quality • Customer cannot retain the actual service. The effect of the service can be retained.

17. Cost of Quality The cost of carrying out the company’s quality functions (meeting the quality needs of the customers) are known as costs of quality. Four categories: As per ASQC Cost of Prevention Cost of Appraisal Cost of Internal failures Cost of external failures

18. Cost of Prevention • Costs incurred in planning, implementing and maintaining a quality system. • Includes Salaries. • Incurred to keep failure and appraisal costs to a minimum. • Cost of quality planning – market research, product development, inspection plan • Cost of documenting • Process control cost • Cost of training • Costs associated with preventing recurring defects • Cost of investigation, analysis and correction of causes of defects by QC and Engg. Deptt. • Cost of cost consciousness programmes

19. Cost of Appraisal • Costs associated with the measuring, evaluating or auditing products, components and purchased materials to assure conformance with specified standards. • Cost of verification- incoming , in-process, after production • Cost of quality audits (appraisal of the quality system) • Cost of inspection equipments, maintenance, Calibration • Cost of vendor rating

20. Cost of internal Failures • Costs associated with defective products, components and materials that fail to meet quality requirements and result in manufacturing losses. • Scrap • Rework or rectification • Re-inspection • Downgrading • Waste • Failure analysis • Lost production time

21. Cost of external failures • Costs which are generated because of defective products being shipped to customers. • When product does not perform satisfactory after ownership is transferred • Repair and servicing • Customer Complaints • Returns • Loss of goodwill

22. Economics of quality of conformance

23. Value of quality “ Return direct or indirect gained by the manufacturer due to mission of quality control”. It is composed of • Value inherent in the design • Value inherent in the conformance to that design

24. Continue… Difficult to assess the value of quality. Factor for assessment: • Saving due to increased production • Reduction in scrap and rework cost • Increased sales of good quality product • Indirect factors such as a. Reputation of manufacturer and goodwill of the customer b. Psychological stability in the enterprise

25. Guru’s of TQM • Walter. A. Shewhart - TQC & PDSA • W. Edwards Deming - 14 Points & PDCA • Joseph. M. Juran - Juran’s Trilogy • A. Feiganbaum - Customer requirement, CWQC, Employee Involvement, TQC.

26. Guru’s of TQM • Kaoru Ishikawa - Disciple of Juran & Feigenbaum. TQC in Japan, SPC, Cause & Effect Diagram • Philips. B. Crosby - Four Absolutes-Quality-Req, Prevention of NC, Zero Defects & Measure of NC • Taguchi. G. - Loss Function

27. W. Edwards Deming • Focus on bringing about improvements in product and service quality by reducing uncertainty and variability in goods and services design and associated processes (the beginning of his ideas in 1920s and 1930s). • Higher quality leads to higher productivity and lower costs. • “14 Points” management philosophy. • Deming Cycle – Plan, Do, Study, and Act.

28. Deming’s 14 points for management • Point 1: Create and publish Vision and Demonstrate Commitment • Point 2: Learn the new Philosophy • Point 3: Understand purpose of Inspection • Point 4: Stop Making Decisions Purely on the Basis of Cost • Point 5: Improve Constantly and Forever the system • Point 6: Institute Training • Point 7: Teach and Institute Leadership

29. Deming’s 14 points for management • Point 8: Drive Out Fear. Create trust. Create a climate for innovation • Point 9: Optimize the Efforts of Teams , Groups and staff areas • Point 10: Eliminate Exhortationsfor the workforce • Point 11: a) Eliminate Numerical Quotas for the work force b) Eliminate management by objectives • Point 12: Remove Barriers to Pride in Work • Point 13: Encourage Education and Self-Improvement • Point 14: Take Action to accomplish the transformation.

30. The Deming Cycle • Plan: Recognize the opportunity for improvement • Do: Test the theory on a small scale • Check: Analyze results of the test phase • Act: Implement the plan to improve customer satisfaction

31. Joseph Juran • Wrote Quality Control Handbook in 1951, a comprehensive quality manual. • Defined quality as “fitness for use.” • Advocated use of quality cost measurement. • Quality Trilogy: quality planning, quality control, and quality improvement

32. Philip B. Crosby • Wrote Quality is Free in 1979, which brought quality to the attention of top corporate managers in the U.S. • Crosby’s Absolutes of Quality Management include: • Quality means conformance to requirements, not elegance. • Quality comes from prevention. • The only performance standard is Zero Defects (ZD). • The only performance measurement is the expense of nonconformance.

33. Inspection and Quality Control Inspection: Checking of material, product or components of product at various stages, with reference to certain pre-determined factors and detecting and sorting out the faulty or defective items. Quality Control: Effective system for integrating quality development, quality maintenance and quality improvement efforts of various groups in an organization to enable the production to be carried out at most economical level

34. Difference between inspection amd QC

35. Quality Control • A system that is used to maintain a desired level of quality in a product or service • Can be achieved through 1. Planning 2. Design 3. Use of proper equipment and procedures 4. Inspection and taking corrective actions in case deviation is observed

36. Quality Control • Offline quality control • Statistical process control • Acceptance sampling plans

37. Process Control Control: Process by means of which we observe the actual performance and compare it with some standard. If there is a deviation between the observed performance and the standard performance then it is necessary to take corrective action. Quality control: The process through which we measure the actual quality performance, compare it with the standards and take corrective action if there is a deviation.

38. Statistical Quality control When statistical techniques are employed to control, improve and maintain quality or to solve quality problems, it is called S. Q. C. Statistics: is the collection, organization, analysis, interpretation and presentation of the data. It is based on law of large numbers and mathematical theory of probability.

39. Basic Statistical concept The concept of variation: No two items will be perfectly identical even if extreme care is taken to make them identical in some respect. Types of variation: • Within the part itself • Among the parts produced during the same period of time • Among parts produced at different periods of time

40. Reasons for variation • Tool wear • Machine vibrations • Loose bearings • Play between nut and screw of the machine table • Faulty jigs/fixtures • Poor quality of raw material • Carelessness of operators • Fatigue to the operator • Change in working condition • Poor maintenance • Measuring errors

41. Reasons for variation • Causes of variation can be subdivided in to two groups – 1. Assignable or special causes 2. Chance or random or common causes

42. Statistical Process Control using control charts • Control charts: Graphical tool for monitoring the activity of an ongoing process • Shewhart control charts • Proposed by Walter A. Shewhart • Control chart description

43. Universe or Population Sample

44. Variable Data (continuous data) When a record is made of an actual measured quality characteristics, the quality is said to be expressed in variables. Examples: Dimension in mm Hardness in rockwell unit Temp. in 0c Tensile strength in Kg/cm2 Weight in Kg.

45. Attribute Data (Discrete data) When the record shows only the no. of articles conforming and the number of articles failing to conform to any specified requirements, it is said to be recorded by attributes. This method simply notes the presence or absence of a quality characteristic in the parts examined Example: Number of defective pieces found in a sample Surface finish of furniture Cracks in sheet by spot welds (Defective – Parts which do not possess the characteristics of conformity)

46. Quality Function Deployment(QFD) Unit I

47. Quality Function Deployment (Listening to the Voice of the Customer) • What are the qualities the customer desires? • What functions must the product serve, and what functions must we use to provide the product or service? • Based on our available resources, how can we best provide what our customer wants?

48. Quality Function Deployment • Identified by other names - House of quality - Matrix product planning - Customer-driven Engineering - Decision Matrix

49. History • Drs. Shigeru Mizuno and YojiAkao are credited with the initial development of QFD in the 1960’s. Their purpose was to develop a quality assurance method that would design customer satisfaction into a product before it was manufactured. Prior quality control methods were primarily aimed at fixing a problem during or after manufacturing. • First application -- Kobe Shipyards of Mitsubishi Heavy Industries, Ltd. in Japan (design of an oil tanker-1972)

50. History • Adopted by Toyota in 1978; and by many other Japanese companies later on. • First used in the U.S. by Ford in 1983 to counter Toyota’s competition. Has been used by many American companies such as GM, Procter & Gamble, AT&T, Digital Equipment, etc.